Human p38 mitogen-activated protein kinase inhibitor drugs inhibit Plasmodium falciparum replication

We recently demonstrated that human p38 mitogen-activated protein kinase (MAPK) inhibitors reduced in vitro and in vivo replication of the protozoan parasites Toxoplasma gondii and Encephalitozoon cuniculi. In this study, we assessed the efficacy of five p38 MAPK inhibitors to block the replication of Plasmodium falciparum in human erythrocytes cultured ex vivo and demonstrate that the pyridinylimidazole RWJ67657 and the pyrrolobenzimidazole RWJ68198 reduced P. falciparum replication, yielded trophozoites that were greatly diminished in size at 24 h, and that these two agents interfered with stage differentiation. Interestingly, the chloroquine-resistant strain W2 was significantly more sensitive to these drugs than was the chloroquine-sensitive strain HB3. These results suggest that pyridinylimidazoles and pyrrolobenzimidazoles designed to inhibit human p38 MAPK activation can be developed to treat malaria.     

Dissecting muscle and neuronal disorders in a Drosophila model of muscular dystrophy

Perturbation in the Dystroglycan (Dg)-Dystrophin (Dys) complex results in muscular dystrophies and brain abnormalities in human. Here we report that Drosophila is an excellent genetically tractable model to study muscular dystrophies and neuronal abnormalities caused by defects in this complex. Using a fluorescence polarization assay, we show a high conservation in Dg-Dys interaction between human and Drosophila. Genetic and RNAi-induced perturbations of Dg and Dys in Drosophila cause cell polarity and muscular dystrophy phenotypes: decreased mobility, age-dependent muscle degeneration and defective photoreceptor path-finding. Dg and Dys are required in targeting glial cells and neurons for correct neuronal migration. Importantly, we now report that Dg interacts with insulin receptor and Nck/Dock SH2/SH3-adaptor molecule in photoreceptor path-finding. This is the first demonstration of a genetic interaction between Dg and InR.     

Reduced Apparent Photorespiration by the C(3)-C(4) Intermediate Species, Moricandia arvensis and Panicum milioides

The CO₂/O₂ specificity factor of sucrose gradient purified ribulose 1,5-bisphosphate carboxylase/oxygenase from the C₃-C₄ intermediate plants Moricandia arvensis (79 ± 1) and Panicum milioides (89 ± 2) was similar to the respective values of the enzyme from the closely related C₃ species, Moricandia foetida (80 ± 5) and Panicum laxum (86 ± 2). Thus, the kinetic properties of this bifunctional enzyme do not explain the reduced rates of photorespiration exhibited by either of these intermediate species.     

Origin of a substantial fraction of human regulatory sequences from transposable elements

Transposable elements (TEs) are abundant in mammalian genomes and have potentially contributed to their hosts' evolution by providing novel regulatory or coding sequences. We surveyed different classes of regulatory region in the human genome to assess systematically the potential contribution of TEs to gene regulation. Almost 25% of the analyzed promoter regions contain TE-derived sequences, including many experimentally characterized cis-regulatory elements. Scaffold/matrix attachment regions (S/MARs) and locus control regions (LCRs) that are involved in the simultaneous regulation of multiple genes also contain numerous TE-derived sequences. Thus, TEs have probably contributed substantially to the evolution of both gene-specific and global patterns of human gene regulation.     

Comparison of growth limits of Listeria monocytogenes in milk,broth and cheese

Aim: To determine growth initiation differences of Listeria monocytogenes between a cheesemaking context, milk and tryptic soy broth (TSB). Methods and Results: A laboratory‐scale cheese was made with a mix of two strains of L. monocytogenes at four initial pH values, five water activity (a_w) values and two contamination levels at 30°C. Counts of L. monocytogenes were determined at time 0 and after 8 h of cheese manufacture. Milk and TSB at the same pH and a_w conditions were inoculated with the L. monocytogenes mix in multi‐well plates. Growth was determined by plating each well onto Agosti & Ottaviani Listeria Agar after 8 h of incubation at 30°C. Each condition was repeated six times, and growth initiation probability was modelled with logistic regression models. Growth initiation boundaries were obtained for each matrix type. The results showed that the growth limits were matrix dependent. In the three matrix types, a_w was the most important factor affecting the probability of growth initiation. Contamination level affected growth TSB and cheesemaking conditions. Conclusions: The interface wideness and position in cheese, milk and TSB were dissimilar, indicating that the use of models evaluated in TSB or milk could not be used to predict the behaviour of L. monocytogenes under cheesemaking conditions. Significance and Impact of the Study: Predictive models generated in liquid media are not necessarily adaptable to solid food, and the generation of real food models is necessary.     

Metal migration and subunit swapping in ALS-linked SOD1: Zn2+ transfer between mutant and wild-type occurs faster than the rate of heterodimerization

The heterodimerization of WT Cu, Zn superoxide dismutase-1 (SOD1), and mutant SOD1 might be a critical step in the pathogenesis of SOD1-linked amyotrophic lateral sclerosis (ALS). Rates and free energies of heterodimerization (ΔG_Het) between WT and ALS-mutant SOD1 in mismatched metalation states—where one subunit is metalated and the other is not—have been difficult to obtain. Consequently, the hypothesis that under-metalated SOD1 might trigger misfolding of metalated SOD1 by “stealing” metal ions remains untested. This study used capillary zone electrophoresis and mass spectrometry to track heterodimerization and metal transfer between WT SOD1, ALS-variant SOD1 (E100K, E100G, D90A), and triply deamidated SOD1 (modeled with N26D/N131D/N139D substitutions). We determined that rates of subunit exchange between apo dimers and metalated dimers—expressed as time to reach 30% heterodimer—ranged from t_30% = 67.75 ± 9.08 to 338.53 ± 26.95 min; free energies of heterodimerization ranged from ΔG_Het = -1.21 ± 0.31 to -3.06 ± 0.12 kJ/mol. Rates and ΔG_Het values of partially metalated heterodimers were more similar to those of fully metalated heterodimers than apo heterodimers, and largely independent of which subunit (mutant or WT) was metal-replete or metal-free. Mass spectrometry and capillary electrophoresis demonstrated that mutant or WT 4Zn-SOD1 could transfer up to two equivalents of Zn²⁺ to mutant or WT apo-SOD1 (at rates faster than the rate of heterodimerization). This result suggests that zinc-replete SOD1 can function as a chaperone to deliver Zn²⁺ to apo-SOD1, and that WT apo-SOD1 might increase the toxicity of mutant SOD1 by stealing its Zn²⁺.